1. Field of the Invention
The invention relates to a device for fixing a shoe on a pedal of a bicycle or similar machine having a pedal body mounted for rotation about a transverse axis.
The fixing device with which the present invention is concerned is of the kind comprising:
on the one hand, on the pedal body, front stop means situated ahead of the transverse axis and a rear fastening element situated behind the axis, and comprising a rectilinear fastening edge substantially parallel to the axis, and capable of being displaced along a direction substantially orthogonal to this axis, against an elastic restoring force; PA1 on the other hand, upward retaining means provided on the pedal body ahead of the transverse axis so as to cooperate with the complementary retaining means provided beneath the sole; PA1 finally moreover, a wedge adapted to be fixed beneath the shoe sole, this wedge comprising towards its front, front stop means conjugate with that of the pedal and at its rear, fastening means capable of cooperating with the rear fastening edge of the pedal body, it being possible for the engagement of the shoe on the pedal to be obtained by a pressure action of the foot on the pedal, PA1 in that the angle (i) is smaller than the maximum angle of twist wherewith the device still exerts an elastic restoring action on the wedge; PA1 and in that the front stop means and upward retaining means are constituted by one and the same front fixing element, situated ahead of the spindle, fixed relative to the pedal and comprising a practically straight fixing and front stop edge parallel to the spindle, the center of rotation during a twisting movement of the foot, being constituted by a point situated close to the front fastening element.
said wedge comprising at least one lower rearwardly projecting fastening flange delimiting a transverse groove issuing at each transverse end, at least one transverse end of the rear flange being delimited by a side inclined along an angle (i) determined in relation to the transverse direction of the wedge, the disengagement being obtained by escaping the flange towards the top by a twist of an amplitude equal to the angle (i) in a given direction.
2. Description of the Prior Art
A fixing device of this kind is shown by DE-U-86 20 037. Such a device has several drawbacks, in particular the following.
The distance separating the two transverse grooves determines at one and the same time the firmness of the twisting opening action and the upward release of the shoe when the elastic bars come tangentially into contact with the cylinder. It follows therefrom, on the one hand, that the unshoeing angle can only be defined by the end of the elastic restoring action and, on the other hand, that near the disengagement position there is virtually no longer any elastic restoring action. This last consequence is particularly irksome because it does not afford the user any proper control of the release of his foot, and untimely disengagements may occur.
If it is considered that a twisting opening of 20.degree. is already large to enable the cyclist to release his shoe quickly, such an opening angle would be clearly insufficient in a device according to DE-U-86 20 037 to obtain a certain retaining firmness in a twisting action, because the restoring moment causes the sine (which is small) of the angle to operate. Otherwise, a heavy and bulky spring exerting a higher force would be necessary.
The engagement of the device in accordance with DE-U-86 20 037 makes it necessary to engage a sleeve in a type of socket which, on the one hand, may make a "blind" engagement difficult, and on the other hand, requires a center of the twisting rotation of the shoe to be coaxial with the axis of the socket. Finally, the cooperation of the socket and of the sleeve eliminates any possibility of a certain freedom of lateral translation of the shoe relative to the pedal.
Another, a fixing device is known, shown by GB 20 289 (MATTHEWS), and in particular, FIG. 6. According to this document, the conditions for fixing and separating the shoe relative to the pedal are defined imprecisely, so that the reliability of the device is not completely satisfactory. Moreover, the vertical pressure of the shoe on the pedal is accomplished with a certain elasticity which is not desirable for sports pedalling.
Moreover, GB-20 289, like U.S. Pat. No. 4,538,480 and U.S. Pat. No. 4,640,151 show that it is known and advantageous to recess the undersole fixing means into the shoe sole so that the cyclist's walking is not impeded.
The primary object of the invention is to provide a fixing device which decreases or eliminates the drawbacks set out with reference to DE-U-86 20 037.
Another object of the invention is to provide a fixing device which, whilst ensuring a good fastening of the shoe on the pedal, makes it possible to obtain a reliable release of the shoe relative to the pedal during a rotational movement of the foot, whilst offering a relatively constant resistance moment during this rotational movement.
In other words, the invention aims to provide a fixing device allowing the release of the shoe in relation to the pedal with a substantially constant resistance or firmness when an angle of rotation has been reached.
Furthermore, it is desired to ensure a firm grip of the sole on the pedal. It is also desirable for the wedge to have small dimensions, so that when it is set into the sole, a large sole area is maintained for walking.
According to the invention, a device for fixing a shoe on a bicycle pedal or similar machine, of the kind defined above, is characterized in that the above mentioned inclined side of the rear flange is constituted by a canted surface forming with the adjacent portion of the rear flange an outwardly convex dihedron;
Preferably, each of the transverse ends of the rear flange comprises a canted surface.
Advantageously, the wedge also comprises a lower forwardly projecting fastening flange delimiting a transverse groove issuing at each transverse end, and the four ends of the flanges of the wedge are provided with canted surfaces that are, in particular, parallel in pairs at opposite ends, the dihedrons formed by these cants being outwardly convex.
Preferably, each canted surface provided for the disengagement of the cyclist's foot by an outward rotation or twisting movement is inclined so as to allow the disengagement with an angle smaller than that necessary for the disengagement by an inward twisting movement of the foot. The angle of inclination of the canted surface for the outward release, in relation to the transverse direction of the wedge, is approximately or equal to 20.degree., whilst the angle of inclination of the canted surface for a release by an inward twisting movement is larger, in particular of the order of 30.degree..
Advantageously, the front and rear fastening edges provided on the pedal body, and the transverse grooves of the wedge capable of cooperating with these edges, are arranged to leave scope for transverse sliding of a few millimetres, in particular of the order of 7 mm for the sole and the shoe in relation to the pedal.
The end surfaces of the transverse grooves of the wedge may be arranged in the form of open Vs, the point of the V being respectively turned towards the front for the front surface, and towards the rear for the rear surface.
Viewed in plan, the wedge can have a substantially rectangular shape whose short dimension is orientated along the longitudinal direction, this short dimension being small. The front stop means and the upward retaining means are advantageously constituted by one and the same front fastening element, situated in front of the spindle, fixed relative to the pedal.
Preferably, the distance between the edge of the front stop edge and the rear fastening edge is at most equal to half the transverse dimension of these edges.
Generally, the pedal body comprises a barrel provided with a housing intended to receive the transverse spindle. Preferably, the distance between the stop and fastening edges is substantially equal to the outer dimension of the barrel.
The front stop element is advantageously constituted by a metallic wire, in particular, a high strength steel wire anchored in the pedal body. This wire forms a hoop and has, at the ends of one straight portion constituting the front stop edge, two curved portions substantially orthogonal to the median plane of the pedal, capable of transversely surrounding the forwardly projecting flange of the wedge. The diameter of the steel wire is small, preferably approximately 3 mm.
The rear fastening element may also form a hoop comprising a straight transverse bar provided at its two ends with curved portions forming radially orientated arms for an articulation about a transverse pin, the rear flange of the wedge being capable of being engaged under the bar, whilst being transversely surrounded by the arms.
The ends of the arms remote from the bar may be coiled so as to form two torsion springs; these torsion springs are advantageously accommodated in a recess of the pedal body, the ends of the springs being directed rearwardly and bearing against a side.
The invention also concerns a cyclist's pedal for use with a fixing device such as defined above.
The invention further concerns a wedge intended to be fixed under the sole of a cyclist's shoe so as to cooperate with a device for fixing the shoe on a pedal, in particular as defined above, this wedge comprising a transverse front groove and a transverse rear groove. In accordance with the invention, such a wedge is characterized in that the end surfaces of the transverse grooves of the wedge comprise recesses communicating with the outside via the end and/or the side, in particular to facilitate the removal of earth or mud lodged in the transverse grooves.
The end surfaces of the grooves of the wedge each comprise four posts, that is to say, two median posts and two lateral end posts corresponding to upwardly projecting wedge portions transversely separated from each other, the median posts being interspaced from each other, whilst the end lateral posts are offset towards the median transverse line of the wedge in relation to the median post.
Preferably, the front and rear median posts form respective front and rear ends of longitudinal ribs having a transverse external extension, a provision being made for a hole in the portion of the wedge comprised between the ribs to allow the central recesses to communicate with the outside, whilst a provision is made for a lateral recess on each side of the wedge between the lateral posts situated on the same side, this recess communicating via a passage with the front and rear recesses.
The invention also concerns a sole of a cyclist's shoe intended to be provided with a wedge for a fixing device as defined above, this sole being characterized in that it comprises a recess capable of receiving the upper part of the pedal.
Advantageously, the sole comprises an inner sole made of a rigid material for fixing of the wedge, and an outer sole made of a relatively flexible material having the above mentioned recess, the covering surface of the outer sole extending situated beyond the wedge to prevent wedge with the ground when the user is walking with a shoe provided with such a sole.
Apart from the arrangements set out above, the invention consists of a certain number of other features which will be discussed in greater detail below with regard to a particular embodiment described merely by way of example with reference to the attached drawings, but which is in no way restrictive.